Microeconomic Theory: A mathematical approach by James M. Henderson and Richard E. Quandt. In the twentieth century, since the thirties, we have witnessed an increasing application of mathematical methods to nearly every branch of economics. The theories of individual optimizing units and market equilibrium which are included within the microeconomics branch are no exception. Traditional theory has been formulated in mathematical terms, and the classical results proved or disproved. The use of mathematics has also allowed the derivation of many new results. Mathematical methods are particularly useful in this field since the underlying premises of utility and profit maximization are basically mathematical in character.